And this is from the Lockheed website:

U-2 Dragon Lady
U-2: Real-Time Intelligence, Surveillance and Reconnaissance on a Moment’s Notice

The U-2 high-altitude reconnaissance aircraft continues to serve as America’s Sentinel of Peace. Current U-2s are equipped with the latest, most advanced signals intelligence (SIGINT), measurement and signature intelligence (MASINT) and imagery intelligence (IMINT) sensors in the Air Force inventory. The U-2 supports intelligence, surveillance and reconnaissance (ISR) requirements in all weather and light conditions, enabled by dynamic airborne retasking capability. A Distributed Common Ground Station (DCGS) can replan and execute new U-2 collection plans as quickly as the U-2 pilot can push a button. Time-sensitive and highly perishable intelligence is collected to provide the National Command Authority and theater commanders with information for situational awareness, geo-political warnings and indications, battlefield surveillance, targeting and battle damage assessments.

Early models of the U-2 (“A” models) began service in the late 1950s. Today, the U-2 S model is 40 percent larger and carries four times the intelligence collection payload. After 45 years of operation, the U-2 was officially recognized in 1998 for service to the nation by receiving the coveted Collier Trophy award for outstanding aeronautical achievement. Today, the aircraft they said “could not be built and would last a few years” has celebrated over 50 years as a national asset.

The flexibility of the U-2 over satellites ensures that the U-2 will be the first to arrive and the last to depart. The nation will continue to rely on the U-2 for dependable, accurate and time-sensitive ISR information for years to come.